Roger D. Hibberd

The Probot--an active robot for prostate resection.

Abstract As men age, their prostates can enlarge, causing urinary difficulty. Surgery to correct this [transurethral resection of the prostate (TURP)] is a skilled and time-consuming operation requiring many repetitive motions of a cutter. A robot has been developed to perform these motions, relieving the surgeon of much of the burden of surgery. This robot has been tried both in the laboratory and later on human subjects and has proved itself capable of performing prostate resection. The Probot system consists of on-line imaging and three-dimensional prostate model construction, an appropriate surgeon-computer interface, a counterbalanced mounting frame and a computer controlled robot.

Robot assisted knee surgery

Discusses establishing a force control strategy incorporating active motion constraint. The following subjects are considered: problems with conventional surgery; robot assisted surgery; control strategy; representing the motion constraint; design of the desired position; force control strategy; implicit force control; modified damping control; experimental results. >

Active compliance in robotic surgery—the use of force control as a dynamic constraint:

Abstract Robotic surgery can be carried out automatically by using a robot to move the cutting tool under position control. However, although the surgeon can observe the procedure on a visual display and has the ability to stop the operation in an emergency, he has little direct contact with the task. An alternative approach is to involve the surgeon more directly, by his moving a robot using active force control. The robot is then used to allow motion in preprogrammed regions, by the surgeon back-driving the robot motors, while preventing motion in prohibited areas. This active constraint robot (or ACROBOT) is described in this paper applied to knee surgery, in which the knee bones are accurately machined to allow the fitting of prosthetic knee implants. The ACROBOT is, however, ideally suited to a range of surgical procedures, because it allows the surgeon to feel the forces exerted during cutting and take appropriate action. This ability to be in direct control, while being constrained to cut within a permitted region, enhances safety and makes the system more acceptable to the medical community. The system of programmable constraint also allows the ACROBOT to provide the traditional benefits of robot surgery, namely the ability to machine complex geometrical surfaces very accurately and to make repetitive motions tirelessly. The system also has a potential for minimally invasive procedures. In knee surgery, for example, the robot could operate through a small incision in the skin and excise a volume into which a small, specially designed, unicompartmental prosthesis could fit.

Experiences with robotic systems for knee surgery

Robots have the potential to assist in orthopaedic surgery and improve the outcome of prosthetic implants. Robots have high positional accuracy, and so can achieve the geometrical precision necessary for implanting prostheses into the tibia and femur but poor tactile response, so are not good at assessing the forces required to apply to a cutter while resecting bone; while surgeons have a good tactile sense, and are able to sense changes in bone density, and adjust cutting forces to match. A system is described here that exploits the synergy between robot and surgeon. A force controlled pobot is used, guided from the end-effector by the surgeon. The robot exploits a software based motion constraint system to ensure that the surgeon cannot move a cutting device connected to the robot outside of a safe region, or resect more bone than is required. Thus, the surgeon retains his tactile sense of the bone, while the precision of the robot allows the bones to be cut accurately. Preliminary results are presented in this paper. More complete details of the robot and system performance will be presented at the symposium.

A surgeon robot for prostatectomies

Describes work which has resulted in a prototype robotised system for the removal of prostatic tissue. Preliminary feasibility studies are described followed by a series of clinical trials of a manually driven safety frame, specifically configured to give the required motions of the cutter within a safe constrained envelope. The design of a patented device is then described which is based on the mechanics of the safety frame, but is driven by a series of rare earth servomotors under the control of an interactive software system. The merits of this type of operation are discussed together with some of the safety implications.<<ETX>>

ACROBOT - using robots and surgeons synergistically in knee surgery

A new robotic system is described that exploits the synergy between robot and surgeon in which a force controlled robot is used, guided from the end-effector by the surgeon. Robots have the potential to assist in orthopaedic surgery and improve the outcome of prosthetic implants. Robots have high positional accuracy, and so can achieve the geometrical precision necessary for implanting prostheses into the tibia and femur but poor tactile response, so are not good at assessing the forces required to apply to a cutter while resecting bone; while surgeons have a good tactile sense, and are able to sense changes in bone density, and adjust cutting forces to match. The robot exploits a software based motion constraint system to ensure that the surgeon cannot move a cutting device connected to the robot outside of a safe region, or resect more bone than is required. Thus, the surgeon retains his tactile sense of the bone, while the precision of the robot allows the bones to be cut accurately.

A telemanipulator system as an assistant and training tool for penetrating soft tissue

The requirements are described of a telemanipulator system for assisting in the penetration of soft tissue for medical tasks. A simulation model of events is required to control the procedure. The same model can also be used by the telemanipulator for training purposes. The underlying theory and control of a telemanipulator demonstrator is described, together with a discussion of system requirements. A number of test results are discussed which illustrate the capability of this mechatronics device for use both as a surgeon assistant and as a training aid.

Interactive Pre-Operative Selection of Cutting Constraints, and Interactive Force Controlled Knee Surgery by a Surgical Robot

This paper describes a low-cost computer system that takes CT images of the knee, and with three-dimensional models of knee prostheses allows a surgeon to position the prosthesis correctly pre-operatively in an interactive manner. Once in position the computer can process bone and prosthesis geometry to derive a set of constraint boundaries that constitute a safe cutting area for a force controlled robot (i.e. that avoids soft tissue such as ligaments), and provides the correct cutting planes for good prosthesis/bone alignment. This boundary information is used to program the robot, allowing a surgeon to move the robot within predefined regions to machine away bone accurately whilst preventing damage to soft tissue.

Prostatic resection: an example of safe robotic surgery

A special-purpose robot for prostatectomies has been developed. Details of the robot mechanism, control system and human/computer interface (HCI) are discussed with special emphasis on software methods to ensure system safety. The clinical application of the system is described and software requirements for operating-theatre use are indicated. These requirements include safe error recovery, facilitation of reliable surgical procedures, and an effective HCI.

The use of ultrasound in automated prostatectomy

A new way of applying transurethral ultrasound scanning in the common surgical procedure of the transurethral resection of the prostate is described. The scanning is incorporated as part of a robotic procedure for surgery, so that the overall time spent in an operation can be further shortened, and a safe and accurate operation can be achieved. The prostate dimensions obtained pre-operatively by the transrectal method and those obtained operatively are compared. A robotic system, which was developed specifically to remove prostatic adenoma automatically, is discussed. The system, called a motorised frame, is briefly described, together with its predecessor, a manual frame, in relation to ultrasound measurements. Sizing of the prostate pre-operatively using transrectal ultrasound methods is discussed, using both the manual and the motorised frame. The shortcomins of transrectal ultrasound for use in a robotic procedure are highlighted.